You really need to shop around and you need to personally decide what type of package will suit you best. What's best for me might not be best for you.
You are probably aware that a lot of ISP's are providing "capped" services now, these can prove cheaper if you are a relatively light user.
Don't just stick with Tiscali as 'cos you think it would be easier. Check out click here and use the comparison tool click here to see how they all compare.
I don't know whether you are Pay Per Minute or Unmetered usage at the moment but bear in mind that you can still keep your Tiscali email address even if you change ISP's (I have) and simply configure your Mail account to send mail via your new ISP's mail server.
My only advice would be not to choose an ISP with a 12 month contract 'cos that's a long time to wait if you make the wrong decision and prices are changing frequently at the moment.
Some ISP's to look at - Tesco (new and with 12 month contract), Pipex (offer capped and uncapped connections), my ISP Metronet, the first PayAsYouGo ISP.